The present invention seeks to improve on the type of cardiopulmonary bypass pumping apparatus shown in prior U.S. Pat. Nos. 4,134,425 and 4,293,961, both issued to Runge. In both of these patents, a compressible tubing shunt is utilized in the compression chamber of a pulsatile flow pump. The compressible shunt in both patents is equipped with interior proximal and distal valves near opposite ends of the pump compression chamber. The manufacturing of shunt tubing from polyurethane or the like with internal valving is quite expensive, particularly where such tubing is used for one operation only and then discarded. Also, the internal shunt valving causes some hemolysis.
Because of the above, it is highly desirable to provide a cardiopulmonary bypass pumping system in which valveless tubing for the shunt may be employed, and it is the objective of the present invention to satisfy this requirement in an efficient, economical and operationally safe and reliable manner.
More particularly, in accordance with the present invention a pair of gravity biased freely pivotally suspended valve roller elements are provided within the compression chamber or housing of the pump near opposite ends of the chamber to act on the exterior of the shunt tubing so as to close off and open the shunt tubing to control blood flow therethrough in a prescribed repetitive cycle of operation. The gravity biased valve elements respond directly to fluid pressure in the shunt at two points near opposite ends of the pump compression plate beneath which a compressible sack of the shunt is located.
Other objects and advantages of the invention will become apparent during the course of the following description.